The broad objective of this research is to make a comprehensive study of uric acid elimination by the avian kidney. We have investigated some basic qualitative patterns and quantitative aspects of uric acid excretion and some specific aspects of urate handling by the kidney. Our future research objectives involve detailed study of urate excretion with emphasis on how the avian kidney handles the potential "solubility" problems of urate elimination. We will determine the location of urate secretion in the avian nephron, the role of pH and divalent cations in urate precipitation, the chemical and physical forms of urate in the urine, the types of renal cellular changes that result from high levels of protein intake, and the role of renal mucoids in the conversion of urate colloids from lyophobic to lyophilic states.